This research will investigate the hormonal regulation of lipoprotein lipase activity at the vascular surface of perfused heart and adipose tissues. The level of functional enzyme activity will be determined both chemically and in terms of capacity to clear perfused lipoprotein triglyceride. Using the normal and streptozotozin-diabetic rat as experimental models, we will investigate the roles of insulin, glucagon and catecholamines in the regulation of blood triglyceride metabolism. The results to be obtained should provide new information on the nature of diabetic hypertriglyceridemia and in normal metabolism, on the regulation of plasma triglyceride hydrolysis in feeding and fasting.